The message here is simple, either get rid of the Welfare state, or close the borders (I'm in favor of abolishing the welfare state, but that's not at all feasible). Amnesty only removes the incentives of aliens to continue working in the jobs that "American's don't want" and makes being a charge of the state more profitable, not at the fault of the alien, but in the self-interest of the politicians. The more people on the government dole, the more power they wield. After all, a check is more tangible and easier to sell than liberty. The common statist argument is that illegal aliens are not privy to government benefits. Assuming that no fraud exists, that doesn't exempt the fact that by distortion of the Citizenship Clause of the 14th amendment, their children are eligible. (Wong Kim Ark 1898). This provides further incentive to not only give birth to a child on American soil, but the more children you have the more money you receive. This is no fault of the alien, they're merely doing what's best for their own self-interest within the construct of the law. A clear example of how people tend to react to the economics of laws (incentives) . Gone are the days when foreigners would emigrate to the U.S. for opportunity, but today rather, for outcome.
Non-assimilation in a literal and figurative sense, pays for the alien and the politician, as it does for other "sub-cultures' in America. It keeps the money rolling in the for the individual in the non-assimilated community, and the amount they receive directly correlates to the amount of power the politician wields. Who would vote against their own self-interest? That's not to mention the enormous benefits to the race hustlers that encourage balkanization and glorify multiculturalism, at the behest of their own self-interest.
The problem is thus, when a conglomerate of the body politic (be it a business, union or voting block) and governments self-interest are congruent, ensuring the survival of that specific group which would not survive in the marketplace--only enabled and perpetuated by government--is a form of corporatism broadly defined (almost a perverted version of Director's law in this sense). A vote is exchanged for government largesse and payments in kind (housing, etc.), these benefits continue to grow and soon the amount paid is greater than the amount earned/produced by entering the marketplace. This comes at the expense of taxpayer, who receive no actual benefit, but is forced to subsidize (be it bad business, unsustainable pay or dependency). This also comes at the expense of production, as it no longer pays to gain the skills necessary for advancement in the marketplace. This is anathema to the individual and antithetical to the Constitution, which maximizes individual liberty and restricts the power of government. A sub-culture would never be able to compete with that of the American culture, as we have seen in the world marketplace, if not for the subsidization by taxpayers on the behalf of government self-interest/power.
Clearly, the goal is to not make balkanization and inferior cultures in opposition of the American ideal profitable. As the the system is set-up, the sub-cultures are subsidized by government and discourage assimilation of the cultural values instilled in the successful American tradition. Their assimilation and individual productivity would come at the expense of the political power held by the state, a reason why this form of corporatism will go on in perpetuity. When in history has government not tried to increase its power or grow in size? This example can be juxtaposed by the open immigration policy prior to 1914, before the welfare state. During this period, far more distant and diverse cultures were entering the country at an enormous rate, yet coalesced to the prevailing American ideals. The Italians, Slavs, Jews, Poles and Irish didn't come here to remain as such, they came here to be American, a far better alternative to their motherland. It was their only choice, learn english, get a job and climb the economic ladder as high as possible, which they lacked the liberty to do in their mother country.
Moreover, contrary to the opinion of race hustlers, culture has nothing to do with race. The American culture is made up of many different races that coalesced around American principles while still retaining their ethnic diversity (the "melting pot"). To deny that one culture can be superior to another is to deny an a posteriori understanding of cultural history.